Magnesium in tap water

[Alex C]

Being following this with a bit of interest. A question I have is how do increasing levels of SO4 impact life (plants and fish) in the aquarium, if at all?

It seems the most common compound to get Mg into the ferts is using MgSO4 so bumping up the Mg value to reach the desired Ca:Mg ratio will, if using MgSO4, mean a rise in SO4 too.

I know we need sulphur in there although I've not come across any 'target' amounts as is the case for NO3 etc.

 

[Witcher]

hey @Alex C it doesn't necessarily needs to be mgso4, but Epsom Salts (mgso4) are easy available, you can also use mgno3, mgcl, mghpo4 mghco3 - you just need the easiest available form of mg - and that's it.
I personally prefer to keep sulphates (so4) and chlorides (cl) very very low - | think they are more close to micro than macro in terms of amount we need them.

 

[Maxplantinstitute]

I am also interested in this topic.
It seems like I need to add intolerable amounts of Mgso4 to my tank. Or else some plants will suffer and this might be the reason some other plants are stunted.
Not 100% sure about this yet, but trying out different solutions for this.
There are other sources for magnesium available.
Rotala butterfly calc. Lists magnesium gluconate, and on eBay there Are a lot of sellers offering magnesium glycinate.

Could one of these two be a better alternative for magnesium in a planted aquarium?
I am a total noob when it comes to chemistry and I have no idea what glycinate means...... Or does.

 

[Craig Matthews]

@Zeus. So we have our ca/mg ratio sorted bye adding the mg sulphate after water change to make a 3:1 ratio but the pottasium is not at mg-k 1: 0.75 ratio so are we adding the k at water change also achieve a 3:1:0.75 CA/mg/k ratio to create our baseline and nutrient taxi service then adding the 7:1:10 npk ratio on top via macro and micro days as normal, this is what my thoughts are.Alot of consideration but we maswell lay all out on the table and thanks for the maths help I divided mg/k rather than k/mg

 

[Zeus.]

A question I have is how do increasing levels of SO4 impact life (plants and fish) in the aquarium, if at all?

As far as I'm aware none but @dw1305 may have a better answer

It seems like I need to add intolerable amounts of Mgso4 to my tank. Or else some plants will suffer and this might be the reason some other plants are stunted.
Not 100% sure about this yet, but trying out different solutions for this.

Been struggling with my plants for some time and have come across this ratios a few times, but unfortunately didn't do the relevant reading 😳🙄

Could one of these two be a better alternative for magnesium in a planted aquarium?

Dunnu @dw1305 again - but think Epsom salts are fine.

@Zeus. So we have our ca/mg ratio sorted bye adding the mg sulphate after water change to make a 3:1 ratio but the pottasium is not at mg-k 1: 0.75 ratio so are we adding the k at water change also achieve a 3:1:0.75 CA/mg/k ratio to create our baseline and nutrient taxi service then adding the 7:1:10 npk ratio on top via macro and micro days as normal, this is what my thoughts are.Alot of consideration but we maswell lay all out on the table and thanks for the maths help I divided mg/k rather than k/mg

Well still in the working 'stuff' out phase but my initial plan is

1.Use the Ca added per WC and a Mg to suit ratio of Ca:Mg of 2:1 taking the taps waters [Mg] and corresponding Mg added to tank at WC.

2. Ignore the ppm of all elements left in tank after draining water for WC as long term it will be irrelevant a few WC down the road and the Ca:Mg ratio will be between 3:1 and 2:1

3. Then for the adjust the Mg ppm of tank after water change- add epsom salts (for my 500L its about 150g Epsom salts) to suit Ca:Mg ratio.

4. use Half the tank Mg ppm for baseline K ppm and play with salts for macros to get the N: P :K ratio of 7:1:10

5. dose the K three times a week with other macros

I have done the initial maths for macros ( just need to recheck a few times) and it works out to about 1/3 of what Clive advises. Not that Clives is wrong OFC its a case of what works and he did have high light.
Plan to set new fert regime off on Sunday and watch the plants.

 

[Sammy I]

I use to have a problem with my hygrophila polysperma leaves rolling up when i dosed mgso4 and k2so4 together. As in i use to dose the APF recipe and realised it wasn't "full" EI and needed to up my k. So instead of adding extra k to my solution i added a little bit during water change.

I think i use to add 2.5tsp mgso4 to my 125l tank that would give me 10ppm MG, 13ppm S. Also for the extra k i got some k2so4 and would dose just under 0.5tsp to get about 10ppm K, 4ppm S. The polysperma leaves, mainly the upper nodes use to become all twisted or rolled up inwards. I don't know what was causing it, but it would happen pretty much overnight after a water change. Dosing a little bit less mgso4 and adding the k2so4 to my solution seemed to help. So no idea what it was, have always wondered about the S, from both.

 

[jaypeecee]

Maybe we should be working backwards with our hard water- Calculate the Calcium we add each week with our WC, what Ca:Mg:K ratio we are going to use, then when we have our [Mg] per week we will have our target [K] and from there apply the N: P :K ratio of 7:1:10, kinda makes some sense in a way!!

Hi @Zeus.

For my benefit (and maybe others), how does the Ca:Mg:K ratio relate to the Nitrogen : Phosphorus : Potassium ratio*? What's the connection?

* I've had to write it this way. If I use the element names - N, P and K - I get emoticons popping up!

JPC

 

[Zeus.]

Well first of all I am no expert OFC

But been struggling with some of my plants for some time and keep coming up with the ratios in my reading around and didn't do much about it 🙄

But was about to implement T Barrs 7:1:10 [N : P :K] as hes is one of our peers as is D Wong who mentions the ratio in his 2hr Aquarist in the in depth Nutrient dosing

The Ca:Mg:K ratio I have heard about for a while but as above did little to implement it 🙄

The connection is it applies to our 'plants' the two different ratios I have never seen linked before, but both have a common factor Potassium (K) so IMO they should be linked. As if one is to be used why shouldn't we be using the other and they have Potassium in conman

So why shouldn't we have



it just makes sense that plants take up nutrients in certain ratios, they may not be all the same but they will be similar, use other folks work/data/theroys and it it try!!!!

So the maths to link the ratios together with 'K' is


which results in



or


depending on which Ca:Mg ratio your aiming at.

Seeing that the [Ca] is high in folks with hard water start with that and work the other ppms out.

and if you need to increase say your [NO3] you also need to increase the rest of the elements ppm to keep the elements in the ratio.

There is an 'element' of a 'leap of faith' OFC but it just seems to make sense.

I've had to write it this way. If I use the element names - N, P and K - I get emoticons popping up!

same here 😛😛😛 hence Ive been posting [N : P :K]

If your using RO water there are lots of others who have the right fert mixes who get the plants to look great so you just copy their fert regime.
Maybe with hard water it just needs another approach and maybe the ratios is a possible solution!

 

[Zeus.]

Done a bit more reading around

and there isnt an NPK ratio that suits all plants its more of a guidelines and dosing Macro ferts in excess and what seems to work, which makes some sense as when I was working out some NPK ratios do you use the mass of N,P and K or the mass of NO3, PO4 and K as using the former gives a completely different ratio than the later, with the former making it very difficult to even achieve with the salts! and the resulting doses of NO3,PO4 and K not in the range to what our peers advise in the EI range

So was thinking I will apply the Ca:Mg:K ratio then apply the ratio of Clives NO3: PO4:K macro mix with [K] being the link and see how it goes.

Then I read Balancing Calcium and Magnesium and T Barr had quite a few interesting posts - that I will be reading again tomorrow 😉

 

[Craig Matthews]

I think I'll have a read of that to zeus at present I'm trying the CA,mg,k ratio with Clive's ei mix method on top which no matter how much light is sufficient we will not have a defiency. My plants look greener ,andcrisp and fresh also one of my plants have began to grow again which was dorment for sometime and my staghorn algae has not come back. I keep updating about my progression

 

[Craig Matthews]

@zeus I understand what you are implying about needing to add more calcium if we raise our no3,po4 etc but of we use Clive's ei mix then its its maximum our tank should ever need? Our plants need so little of CA that if the ratios were to favour npk then would it really matter as We are trying to tone down the CA ions with the ratios?

 

[Witcher]

Hey @Zeus. I'm sorry for overcomplicating you ratios but I think you'll also need to introduce C and H into your ratio calculations - for example (C)55 : (H)72 : (O)5 : (N)4 : (Mg)1 is the chlorophyll a ratio.

 

[Alex C]

when I was working out some NPK ratios do you use the mass of N,P and K or the mass of NO3, PO4 and K as using the former gives a completely different ratio than the later, with the former making it very difficult to even achieve with the salts!

Surely the NPK ratio is the mass of NPK rather than NO3 etc. My understanding is we use NO3/PO4 as that's the form the plant can uptake the respective nutrients in (I may be very very wrong in which case I need to go back and reeducate myself!) so it just makes calculating dosing easier aiming for NO3 ppm rather than saying "we need x N, now what value of NO3 do we need..." etc etc.

Per the EI article the max uptake PPM for NO3, PO4, and K was 20:3:30, which (if i've done my maths right) would translate to a NPK ratio (based on PPM) of 4.6:1:30.6. I'm at work at the moment but will put together a ratio by weight later.

 

[Zeus.]

My plants look greener ,andcrisp and fresh also one of my plants have began to grow again which was dorment for sometime and my staghorn algae has not come back.

I think the results should speak louder than any ratios for any given tank

I'm sorry for overcomplicating you ratios but I think you'll also need to introduce C and H into your ratio calculations - for example (C)55 : (H)72 : (O)5 : (N)4 : (Mg)1 is the chlorophyll a ratio.

Yes and No - as quoting a specific structure/compound in the plants is too specific, having a general ratio for all the plants components would be helpful, But all plants makeup is different OFC so there will be a range.

Surely the NPK ratio is the mass of NPK rather than NO3 etc

Thats what I thought and Rotala Butteryfly does give the results for each element. But when I tried to get the 7:1:10 ratio for NPK I was unable to as the [K] was always so high

Per the EI article the max uptake PPM for NO3, PO4, and K was 20:3:30

which is approximately 7:1:10 OFC

which (if i've done my maths right) would translate to a NPK ratio (based on PPM) of 4.6:1:30.6.

yep large mass of K which results in [NO3: PO4: K] which dont fit in the EI range for my attempt at the maths 🙄

Need more reading OFC as only just finished for the morning. But dont think we will get a Magic ratio that will work for all. Us with the high [Ca] in our tap waters will probalby just need to add extra Mg to compensate for the 24:1 [Ca:Mg] ratio we have to start with and will need to check to what our resulting [Mg:K] ratios are after adding the extra Mg that the ratio is within acceptable limits. Kinda makes sense.

 

[Zeus.]

Balancing Calcium and Magnesium

'Post #45 -T Barr'

Quote
Ratios themselves have nothing to do with it. This is Liebig's law, the individual concentrations, NOT the ratios, are the limiting growth factors.

1. I can have a perfect ratio and still be "limiting" for example. This goes back the Liebig's law.
2. I can have 25ppm Mg and 2 ppm Ca, no issues, same as above back to Liebig's law
3. I can have 2ppm of Mg and 25ppm of Ca++, no issues.
4. If the ratio is important, how can both cases work equally well?

As long as the nutrients levels are non limiting, they can easily be over a Extremely wide range.
I've had these types of tap water above.
It was only when the Mg was too low have I've ever seen issues.
There is also no research that supports this claim, in agriculture, ratios are use to reduce the COST of wasting expensive fertilizers on crops for specific crops.
Aquarist are not concerned with the small cost factor of dry fertilizer however.
NH4+ is not bad to add small amounts, but that's what the fish load is for.

In plant science, mineral nutrition textbooks also down play the roles of ratios being important, they use Liebig's law and analyze individual nutrients.
In Aquatic biology, they abuse the Redfield Ratio in Phycology and Limnology perhaps more than any other concept.

I think many see some correlation and assume that is meaningful, when they have not demonstrated and tested the alternatives.
Then they assume ratios are important, then this leads to myths.

I've done this for 20 years and falsified many claims about ratios. I've not found any ratios that do as claimed by aquarist.
Ever. Not saying there is not something to them, but I've never once been able to see it in my own tanks.
All it takes is for someone to have a ratio outside the claim and say 10x-100x difference, and the ratio claim is out the window.
This is not difficult to falsify.
Unquote

He does say in earlier posts about most issues being CO2 related and poor husbandry

Goes away to think and

 

[Craig Matthews]

I think we are on the right tracks but we do not need to over complicate things we arnt building space ships for NASA. The ratios obviously matter because of probability of any given ion crossing over a leaf so we need to correct/balance that aspect but with ratios being close enough I think the plants are quite broad in that aspect. Its all about trial and error.

 

[Craig Matthews]

Haha @Zeus. Well we cannot go against our feriors in this hobby but..... Since I've added more mg+k and adjusted to this ratio everything seems better or is it just I simply wasn't adding enough to satisfy my plants demands through means of light and CO2? since we only have hobby grade test kits
( speaking for myself ) we/I cannot test accurately how much is being consumed for each and every nutrient.

 

[jaypeecee]

Hi Folks,

If you haven't already seen the following thread on another forum, it makes for very interesting reading. I really like the very detailed account of everything that 'kekon' did. Very methodical. Note the date of the thread!

https://www.aquaticplantcentral.com/forumapc/fertilizing/41779-how-balance-npk-ca-mg-micros.html

JPC

 

[Zeus.]

Hi Folks,

If you haven't already seen the following thread on another forum, it makes for very interesting reading. I really like the very detailed account of everything that 'kekon' did. Very methodical. Note the date of the thread!

https://www.aquaticplantcentral.com/forumapc/fertilizing/41779-how-balance-npk-ca-mg-micros.html

JPC

Yes read that last night did you see when it was posted ? 07-01-2007

T Barrs Balancing Calcium and Magnesium last post was May 6, 2012

Quote from T Barrs post-I think many see some correlation and assume that is meaningful, when they have not demonstrated and tested the alternatives.
Then they assume ratios are important, then this leads to myths.

Since I've added more mg+k and adjusted to this ratio everything seems better

I think it is the Mg that our tanks need (or was missing)

I do one Macro and trace mix and use them on two tanks 500l and 50l former dosed at 100ml and later 10ml per dose.

Started on APFUK ppm and no real issues for some time


then moved over to Clives guidelines with a Fert adjustment here and there at some time developed a deficiency which seemed to be Fe. So changed over to DIY Trace mic and using Fe EDDHA/DTPA

Was getting mixed results with symptoms coming and going but always struggling with Hygrophila pinnatifida

The only diferance lately is the 500l gets Fe EDDHA and the later gets Fe DTPA, but in the past its been a bit of a mix of both EDDHA and DTPA the light is more intense in the 50l. Both tanks have twinstars/chihiros doctors, Both DCs same colour Yellowish green and the 500l was getting LCO.

The plants always did better in the 50l and it has had me a little perplexed for some time. But things use to be better and there was no sudden change just gradual. So my AS was getting old and I had hard water etc etc......

Tanks was getting worse lately so checked my DIY trace mix and found an error my B and Mo calculations 4/2/2020 fix it, changed the trace mix and small tank has improved quite a bit and some of 500l tank has but Hygrophila pinnatifida, Blyxa Japonica and Ceratopteris thalictroides hasnt with Hygrophila pinnatifida still suffering the worse.

Thats when I revisited this thread earlier this week and checking my Macro mix I spotted another error! -When doing my [Mg] calculations when I was working though the results of my MgSO47H2O grams added to my dosing bottle must off selected MnSO4.H2O by mistake on the Roltala Butterfly page instead of MgSO47H2O which gave about one third less in grams needed to make the dosing solution.
Not realising it made up the solution and dosed away so Mg ppm in tank was one third less than what was planned. Not sure when it happen but it was months ago.It wasn't till I worked though the calculations I spotted that the resultant weekly [Mg] in ppm didnt match the mass of MgSO47H2O added. But when MnSO4.H2O was selected it fitted the results. Result of making adjustments/calculations late at night or after a busy day at work 🙄

Then another penny dropped

500L gets 50% WC weekly no top ups of tap water
50l gets 70 to 80% WC plus top up of tap water

So the 50L was getting more Mg from a bigger WC plus top ups OFC not much but more Mg per week. It was still getting a Ca:Mg ration of 24:1 from the tap water I added

So the extra Mg the smaller tank was getting was nothing to do with a better Ca:Mg ratio and it fits what T.Barr surgest about 'Liebig's law' i.e. Mg was the limiting element.

It will be interesting to see how my Hygrophila pinnatifida responds to the extra Mg in the 500l, the Hygrophila pinnatifida in the 50l looked better to start with and was improving after fixing the trace error fix but after adding some extra Mg a few days ago it does look better again, but is that the extra Mg or the better trace mix!!

For the time being I am with T Barr after all he has done many tanks with different Ca:Mg ratios and he reports that 'Liebig's law' fits the results he has seen, Plus some of his early post in various threads he does suggest a possible possible ratio for ferts, then years later he has dropped the ratio suggestions posting ''Then they assume ratios are important, then this leads to myths.'', so just add some extra Mg if you think its the limiting factor

Time will tell 😀

(Sorry for big post)

 

[Craig Matthews]

@Zeus. If you recall my earlier posts ( maybe a different thread I cannot remember ) I was suffering problems with my hygrohila 53b, hygrohila Compacta and hygrohila araguaia suffering pin holes, pale colouration (N/mg/Fe/K defiency symptoms,) staghorn algae and to soon end up with no growth and leaf drop but the one species you keep mentioning is hygrohila and its the one species I've had problems with maybe its a coincidence?. My java fern was growing,HC was growing but these was still experiencing pale growth and staghorn. Since adding the extra mg and k ( K2SO4 ) all my plants have coloured up and all plants have began to grow again although slowly. Staghorn has gone and not reappeared but its early days. I tried adding extra Fe in the form EDDHA, extra no3,extra po4 but no joy only until I added extra magnesium and k adjusting to these ratio's.maybe its species related or maybe there is something that we and our inferiors are over looking?